1. Field of the Invention
The invention disclosed herein relates to identifying the chemical composition of a material that is located in a borehole. In particular, analysis of the material is performed within the borehole.
2. Description of the Related Art
A variety of geologic formations contain reservoirs of petroleum. Measuring properties of the geologic formations provides information that can be useful for locating the reservoirs of petroleum. In addition, it is important to monitor the reservoirs that are already located. Monitoring provides information useful for optimizing production resources.
Generally, petroleum is accessed by drilling a borehole into the subsurface of the earth. The borehole also provides access for taking samples of materials from the borehole. The samples may be taken to the surface of the earth for analysis in a chemistry laboratory. The analysis is used to determine a chemical composition of a material in the borehole such as a petroleum compound. There are a few disadvantages to analyzing the samples in the laboratory. One disadvantage is that transporting the samples to the laboratory can be time consuming. Another disadvantage is that while samples are being withdrawn from the borehole other uses of the borehole may be precluded. One technique that can overcome these disadvantages is well logging.
Well logging is a technique used to take measurements of the geologic formations and reservoirs from the borehole. In one embodiment, a logging instrument is lowered on the end of a wireline into the borehole. The logging instrument sends data via the wireline to the surface for recording. Output from the logging instrument comes in various forms and may be referred to as a “log.”
Therefore, what are needed are techniques for logging the chemical composition of a material in a borehole.